Around the time of sphaleron freeze-out at \(T \simeq 135\,\textrm {GeV}\) , the temperature dependence of the weak mixing angle represents the dominant effect on the evolution of the hypermagnetic helicity, which allows us to neglect Ohmic dissipation in our estimate of the baryon asymmetry.
In this approximation, the transport equation for the charge density \(q_B\)  in the broken phase obtains the following form [1]},
\(\left(\frac{d}{dt} + 3H\right)q_B = \frac{111}{34}\,\Gamma _{\rm ws}\left[c_B^{\rm dec}\,\chi \,T^3 - \left(q_B-\bar{c}_{\rm sph}\,q_{B-L}\right)\right] \,.\) 
